If trends continue without scale-up of effectiveinterventions, by September 30, 2014, Sierra Leone and Liberia will have a total of approximately 8,000 Ebola cases.

A potential underreporting correction factor of 2.5 also was calculated. Using this correction factor, the model estimates that approximately 21,000 total cases will have occurred in Liberia and Sierra Leone by September 30, 2014.

Extrapolating trends to January 20, 2015, without additional interventions or changes in community behavior (e.g., notable reductions in unsafe burial practices), the model also estimates that Liberia and Sierra Leone will have approximately 550,000 Ebola cases (1.4 million when corrected for underreporting).

These large numbers made headlines everywhere.

CDC director Thomas Frieden, MD released a the following statement regarding the EbolaResponse model yesterday:

The Ebola case estimates published today in the MMWR are based on data from August and reflect a moment in time before recent significant increases in efforts to improve treatment and isolation. They do not account for actions taken or planned since August by the United States and the international community. We anticipate that these actions will slow the spread of the epidemic.

The Ebola Response model is an important tool for people working to stop Ebola. It provides the ability to help Ebola response planners make more informed decisions on the emergency response to help bring the outbreak under control – and what can happen if these resources are not brought to bear quickly.

The model shows that there are severe costs of delay, and the need for increased resources and immediate and ongoing action by the international community.

It is still possible to reverse the epidemic, and we believe this can be done if a sufficient number of all patients are effectively isolated, either in Ebola Treatment Units or in other settings, such as community-based or home care.